The thrust of this research proposal is to advance fundamental understanding of a relatively new and innovative label-free optical biosensor technology based on porous silicon microcavities. The specific aims are designed to investigate key parameters in the fabrication of an affinity sensor for the detecting Candida. Phage display scFv antibody probes that target cell wall surface antigen will serve as the receptor. A goal will be to discover whether these probes can function in an immobilized format to distinguish between the Candida blastoconidia (noninvasive) and filamentous (pathogenic) forms. Foundation knowledge will be gained on understanding the dependence of the porous silicon microstructure (porosity, pore morphology) and surface chemistry on biomoiecular infiltration and sensor sensitivity. A key aim will be to determine the sensor can detect Candida antigen at levels typically expressed in a primary skin infection. A mouse model of primary Candida infection will be utilized as a source of antigen from skin. To accomplish these goals a reporter assay will be used to quantify the activity of the immobilized scFv probes relative to a solution control. Initial work will be done using devices in a single-probe chip format. The silicon microfabrication facility at the Rochester Institute of Technology will be leveraged to investigate the process steps required to fabricate an arrayed-probe chip format so multiple targets could be assayed simultaneously. Access to this facility will also enable studies to elucidate fundamental insight into the material science challenges of sensor fabrication. The proposed research will generate knowledge that is broadly extensible to the detection of other pathogenic organisms and proteomic conjugates. Essential skills will be acquired that comprise a critical component of the training process to become a successful independent investigator in biomedical sciences.